Electro-magnetic actuating means



Oct. 25, 1955 (5. w. KNIGHT 2,721,953

ELECTRO-MAGNETIC ACTUATING MEANS Filed Aug. 1, 1952 2 Sheets-Sheet 1 "WIM- z2-- 25 a? Z Z... E W ,Z/

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ELECTRO-MAGNETIC ACTUATING MEANS Filed Aug. 1, 1952 2 Sheets-Sheet 2 %7 6 IN V EN TOR. I||l 1 0 4 M 'iiiliiiiii iiiili BY 2 a g United States Patent Cfiice ELECTRO-VIAGNETIC ACTUATIN G MEANS George W. Knight, Milwaukee, Wis., assignor to Allen- Bradley Company, Milwaukee, Wis., a corporation of Wisconsin Application August 1, 1952, Serial No. 302,216

Claims. (Cl. 317-198) This invention relates to electromagnetic actuators for the operation of switch contacts, valves, and the like and it more particularly resides in an electromagnetic actuator having a coil with a field piece and armature disposed in flux conducting relation to the coil wherein the armature is guided in its movement between open and closed positions with respect to the field piece by a member to which it is joined through a kerfed engagement having curvilinear bearing surfaces to provide for a rolling movement of the armature with respect to the guiding member about such curvilinear bearing surfaces upon closure of the actuator to permit alignment of the armature and field piece sealing surfaces.

For proper operation of an electromagnetic actuator sealing of the engaging surfaces of the armature and field piece must be ensured upon closure. To this end it is necessary to provide sufiicient limited freedom of movement for either the field piece, the armature, or both, with respect to a pair of axes substantially perpendicular to one another and disposed in a plane parallel to the sealing surfaces of the armature and field piece. For an actuator that employs an armature that moves with a straight line action, as distinguished from a pivotally mounted armature, it is necessary to provide guiding means to confine the armature in its movement in a straight path. Such guiding also acts to retain the armature, and particularly the sealing surfaces, in parallel aspect with the field piece as it moves toward and away from the same. In some actuator embodiments, having straight line armature action, the armature guiding means travels together with the armature between open and closed positions. Such guiding means is in turn guided as it moves between open and closed positions and it is desirable that the side play of the guiding means be as small as free action and manufacturing tolerances permit. In this manner the bearing surfaces for the guiding means may be constructed so as to give long trouble free life. Small clearances for the side play of the guiding means, however, restrict the necessary freedom of side movement and tilt of the armature for obtaining the requisite sealing of the engaging field piece and armature surfaces.

It is an object of this invention to provide in an electromagnetic actuator a guiding means that moves in conjunction with the armature and is in novel kerfed engagement therewith to allow limited rolling movement of the armature with respect to the guiding means to take place upon sealing of the armature and field piece engaging surfaces which rolling movement is characterized by a continuous contact between armature and field piece progressively along a curved bearing surface comprising a part of the kerfed engagement.

It is another object of this invention to provide in an electromagnetic actuator an armature, having a lengthwise portion that is translated transversely with respect to itself upon movement into and away from sealing engagement with a field piece, that is in guided contact at each end of the lengthwise portion with a guiding member having a crowned bearing surface resting upon 2,721,963 Patented Oct. 25, 1955 the armature about which rolling contact may take place.

These and other objects and advantages will appear in the description to follow. In the decription reference is made to the accompanying drawings which form a part hereof and in which there is shown by way of illustration and not of limitation electromagnetic actuator apparatus in which this invention is embodied.

In the drawings:

Fig. 1 is a front view in elevation with parts broken away and in section of an electromagnetic switch embodying this invention,

Fig. 2 is a side view in elevation with parts broken away and in section of the apparatus shown in Fig. 1.

Fig. 3 is a fragmentary view in perspective of one leg of the contact carrier forming a part of the switch shown in Figs. 1 and 2,

Fig. 4 is a front view in elevation of an alternative form of an armature and contact carrier for the electromagnetic switch of Figs. 1 and 2 in which this invention is also embodied,

Fig. 5 is a fragmentary side view of the armature and contact carrier shown in Fig. 4,

Fig. 6 is a view in section of the armature and contact carrier shown in Fig. 4 viewed through the plane 66, and

Fig. 7 is a view in section of the armature and contact carrier shown in Fig. 4 viewed through the plane 7--7.

Referring now to the drawings, there is shown in Figs. 1 and 2 an electromagnetic switch 1 having a mounting plate 2 upon which is afiixed a magnetic actuating unit 3 and a stationary contact housing 4. The housing 4, formed of insulating material, has a back wall 5 through which mounting bolts, not shown, are passed to extend into threaded engagement with the plate 2 to secure the housing 4 in place. Extending forwardly from either side margin of the back wall 5 is an enclosing end wall 6 and between the vertical forward margins of the end walls 6 extends a front wall 7. Spaced evenly between the end walls 6 are three vertical dividing partitions 8. The housing 4 is thus divided into four are restricting chambers which are each in turn enclosed at the top by strips 9 of insulating material that rest upon cornices 1t) projecting from the near top of each of the end walls 6 and the dividing partitions 8. A pair of stationary contacts one behind the other such as designated at 11, where the forward contact is visible, are mounted on each of the strips 9 and convenient connection terminals such as 12 and 13 are provided one for each contact 11.

The actuating unit 3 has a stationary field support member 14 comprised of a pair of right and left hand half shells 15 and 16. Half shells 15 and 16 are each com posed of insulating molding material and when placed in juxtaposition to one another provide a cavity in which is snugly housed an electrical coil 17 having terminals 18 that extend through the half shell walls. The coil 17 is a solenoid and the cavity within the half shells 15 and 16 circles a rectangular opening 19 that extends through the field support member 14. Bolts 20 and 21 retain the half shells 1S and 16 in position with the coil 17 in place.

The upper portions of each of the right hand and left hand half shells 15 and 16 comprise spaced front and back walls 22 and 23 between which is received a magnetic field piece 24 formed as a yoke that overhangs beyond the ends of the support member 14 to present a pair of downwardly facing sealing surfaces at the yoke ends. The field piece 24 is composed of a plurality of laminations of magnetic material clamped to one another by rivets 25. To mount both the field piece 24 and the field support member 14 in position a bolt 26 is extended through the front wall 22, the yolk 24, the rear wall 23,

and hence into threaded engagement with the mounting plate 2. 7

As is more clearly shown in Fig. 1 the field piece 24 is held by the bolt 26 in a position slightly spaced from the field support member 14. Such a spacing permits for a limited degree of pivotal movement of the field piece 24. The bolt 26 is brought up tight to restrain such movement of the field piece 24 and only upon striking the field piece 24 with a forceful blow, such as may be delivered upon closure of the switch, may the field piece 24 be shifted in position. This permissible shift allows the downwardly facing yoke ends of the field piece 24 to be aligned with an armature 27 in a plane parallel to the bolt 26 for obtaining the requisite seal between itself and the armature 27.

The armature 27, comprised of stacked laminations 28 held in clamped position by rivets 29, extends lengthwise through the opening 19 of the field support member 14 and extends outward to either side thereof to present sealing surfaces in facing relation to the yoke ends of the field piece 24. Each end of the armature 27 is formed with a horizontal groove or kerf 36 that extends aross the entire armature width. A pair of foot-like projections 31 extend from the lower portions of the armature ends and each foot 31 has an upwardly facing bearing surface 32 that comprises the lower side of the adjacent groove or kerf 30.

Shaped to mate with the grooves 39 and the projecting feet 31 for fitted engagement with the armature 27 is a molded stirrup shaped contact carrier 33 of insulating material which comprises an upper horizontal cross-bar portion 34 integrally formed with two downwardly extending legs 35. The cross-bar 34 is provided with a contact mounting rib 36 having openings such as at 37 through which extend movable contacts 38 that bridge between and are in facing relation with each pair of stationary contacts 11. A contact spring 39 is placed beneath each movable contact 38 to urge the contacts 38 upwardly and to provide contact pressure upon closure of the switch 1.

The downwardly extending legs 35 of the carrier 33 curve inwardly at the lower extremity of each to extend about the armature feet 31 and to terminate in bearing pads 49 that slidingly engage the sides of the half shells and 16. Guiding bosses 41 formed as a part of the half shells 15 and 16 are disposed at opposite sides of the pads 49 to cooperate therewith to hold the lower ends of the carrier 33 against inward and outward movement and thus to ensure straight line motion between open and closed positions which are assumed upon movement of the armature 27 between like positions in response to energization and deenergization of the coil 17. A close but free sliding fit between the pads 40 and the guiding surfaces of the half shells 15 and 16 is provided to enhance the life of the bearing surfaces.

Received within the grooves or kerfs of the armature 27 are tongues 42 that project from the inner faces of the contact carrier legs 35. Each tongue 42 has a crowned downwardly facing convex face 43 that rests upon the upwardly facing bearing surface 32 of the respective armature foot 31. The upper faces of the tongues 42 and the upper faces of the grooves 34) are spaced from one another as shown in Figs. 1 and 2. Bearing contact between the armature 27 and the contact carrier 33 is thus made only at the points of tangency between the convex faces 43 and the bearing surfaces 32 and as the armature 27 is moved upwardly and downwardly in response to energization and deenergization of the coil 17, the contact carrier 33 is carried therewith to move the contacts 38 into and out of engagement with the stationary contacts 11.

The contact carrier 33 is guided in vertical movement both by the sliding engagement of the pads with half shells 15 and 16 and bosses 41, as hereinbefore noted, and by suitable close sliding engagement of the cross bar 34 with the walls 22 and 23 that form the upper portions of the field support member 14. The carrier 33 in turn acts to guide and retain the armature 27, in its movement between open and closed positions, in aligned parallel relation with respect to the position assumed when closed with the field piece 24. In order to insure proper sealing between field piece 24 and armature 27 either the armature 27, or the field piece 24, or both, must have limited freedom of tilting movement,

As hereinbefore described, the field piece 24 may pivot about the axis of the bolt 26, to a limited degree. Relative tilt of the armature 27 with respect to the field piece 24 is also provided about a second axis that lies substantially perpendicular to the run of the bolt 26 and which also lies in a plane substantially parallel to the sealing surfaces of the magnetic switch elements. This tilt is permitted by the engagement of the carrier 33 with the armature 27 through crowned bearing surfaces 43 formed as a part of the tongues 42 and plane surfaces 32 of the armature 27. These surfaces diverge from one another to allow the armature 27 and carrier 33 to roll with respect to one another. The necessary roll of the armature 27 with respect to the carrier 33 about the crowned face 43 to a position in mated alignment with the field piece 24 may be accomplished while continuously maintaining engagement between the armature 27 and carrier 33. Shock and colliding contact which would otherwise impair switch life by causing wear of the engaging carrier 33 and armature 27 is minimized.

Another embodiment of this invention is shown in Figs. 4 through 7 where an armature 44 and contact carrier 45 suitable for employment in the switch of Figs. 1 and 2 appear. The armature 44 is formed to provide a pair of inverted L-shaped grooves 46 that present bearing surfaces 47 one at either end, the armature 44 being in other respects similar to the armature 27 of Figs. 1 and 2. The Contact carrier 45 includes a molded upper portion 48 formed for the mounting of contacts which may extend across the top of a field piece such as 24. Two metallic inserts 49 extend downwardly from the molded portion 48 and terminate in short horizontal armature engaging rests 50 that are turned downwardly at their inner ends to form cars 51. Each rest 59 and associated ear 51 is received within an L-shaped groove 46 for engagement with the armature 44. As is shown more clearly in Figs. 5 through 7, the armature engaging rests 50 are cylindrical with convex faces 52 resting upon the surfaces 47 of the armature 44 in a manner similar to the engagement of the face 43 in the switch 1 of Figs. 1 through 3 with the upper face 32 of the armature feet 31. Ample clearance between the armature engaging rests 50 and the armature 44 permits for relative rolling movement to accommodate for proper sealing of the armature 44 with the yoke of the particular actuator with which it will be employed. The ears 51 insure retention of the rests 59 within the grooves 46.

I claim:

1. In an electro-magnetic actuator the combination comprising an actuating coil, a field piece disposed in flux conducting relation to said coil, an armature normally spaced in open position from said field piece and movable to closed position upon excitation of said coil, said armature including a lengthwise portion extending transversely of the direction of armature travel adapted to seal against said field piece upon movement of said armature to closed position, an armature guiding member extending between and joined to the ends of the lengthwise armature portion for movement with said armature between open and closed positions, connections joining said guiding member to the ends of said lengthwise armature portion each including a protruding member extending transversely of the direction of armature travel across a major portion of the width of said armature and a receiving member having a recess extending transversely of the direction of armature travel across a major portion of the width of said armature into which extends the transverse extent of said protruding member, said protruding and receiving members having a pair of facing engaging bearing surfaces one of which is curved to provide rocking engagement between said armature and said guiding member, and guiding surfaces slidingly engaging said guiding member for guiding movement between open and closed positions.

2. In an electro-magnetic actuator the combination comprising an actuating coil, a field piece disposed in flux conducting relation to said coil, an armature normally spaced in open position from said field piece and movable to closed position upon excitation of said coil, said armature including a lengthwise portion extending transversely of the direction of armature travel adapted to seal against said field piece upon movement of said armature to closed position, an armature guiding member extending between and joined to the ends of said lengthwise armature portion for movement with said armature between open and closed positions, tongue and kerf connections joining said guiding member and said armature each comprising mating members formed of the armature and guiding member which mating members present respectively a pair of facing engaging surfaces one of which is crowned to provide rocking engagement between said armature and said guiding member, and guiding surfaces slidingly engaging said guiding member to restrict movement of said guide member upon translation between open and closed positions.

3. In an electro-magnetic actuator the combination comprising an actuating coil, a field piece disposed in flux conducting relation to said coil, an armature normally spaced in open position from said field piece and movable to closed position upon excitation of said coil, said armature including a lengthwise portion extending transversely of the direction of armature travel adapted to seal against said field piece upon movement of said armature to closed position and having a pair of kerfs one at each end thereof with bearing surfaces extending transversely of the direction of armature travel, an armature guiding member reaching from one end to the other of said lengthwise armature portion and having a tongue loosely received within each of said kerfs with a curvilinear bearing face resting upon the bearing surface of the kerf to support said guiding member in rocking engagement with said armature, and guiding surfaces slidingly engaging said guiding member upon translation between open and closed positions.

4. In an electro-magnetic actuator the combination comprising an actuating coil, a field piece disposed in flux conducting relation to said coil, an armature normally spaced in open position from said field piece and movable to closed position upon excitation of said coil, said armature including a lengthwise portion extending transversely of the direction of armature travel adapted to seal against said field piece upon movement of said armature to closed position, an armature guiding member reaching from one end to the other of said lengthwise armature portion and engaged therewith for movement with said armature between open and closed positions, tongue and kerf connections joining said guiding member and said armature each including a member with a kerf having upwardly and downwardly facing side faces and a tongued member having a tongue disposed within said kerf with upper and lower faces in facing relation to said side faces, the ratio of the width of said tongue between said upper and lower faces to the gap distance between said kerf side faces diminishing from a medial portion of said tongue outward to the ends thereof, and guiding surfaces slidingly engaging said guiding member upon translation between open and closed positions.

5. In an electro-magnetic actuator the combination comprising a coil having a central opening and surrounding an axis, a field piece for said coil, an armature extending lengthwise through said coil normally spaced in open position from said field piece movable transversely to the axis of said coil into closed position with said field piece upon excitation of said coil, an armature guiding member reaching from one end of said armature to the other end thereof and engaged to said armature ends for movement with said armature between open and closed positions, tongue and kerf connections joining said guiding member and said armature each comprising mating members formed of the armature and guiding member which mating members present respectively a pair of facing engaging surfaces one of which is crowned to provide rocking engagement between said armature and said guiding member, and guiding surfaces slidingly engaging said guiding member to restrict movement of said guide member upon translation between open and closed positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,064,632 Schmitt Dec. 15, 1936 2,158,480 Peterson May 16, 1939 2,347,934 Christensen et a1. May 2, 1944 2,378,022 Logan June 12, 1945 

